Malaysian authorities are probing new information that the missing plane with 239 people on board dropped to an altitude of 5,000 feet or possibly lower to evade radar detection after it turned back midair.

Investigators are poring over the Boeing 777 flight MH370 profile to determine if it had flown low and used “terrain masking” during most of the eight hours it was missing from the radar coverage of possibly at least three countries, the New Straits Times reported on Monday.

The officials are looking at the possibility whether the plane - with 239 people on board including five Indians and one Indian-Canadian - had taken advantage of the busy airways over the Bay of Bengal and avoided suspicion of military radars.

“The person who had control over the aircraft has a solid knowledge of avionics and navigation, and left a clean track. It passed low over Kelantan, that was true,” the paper quoted officials as saying.

The plane “would appear to be just another commercial aircraft on its way to its destination,” it said.

“It’s possible that the aircraft had hugged the terrain in some areas that are mountainous to avoid radar detection.”

This technique is called terrain masking and is used by military pilots to fly to their targets stealthily, using the topography to mask their approach from prying microwaves.

The officials said this type of flying is considered very dangerous, especially in low-light conditions and spatial disorientation, and airsickness could easily set in.

“While the ongoing search is divided into two massive areas, the data that the investigating team is collating is leading us more towards the north,” sources said.

Prime Minister Najib Razak last week said authorities are trying to trace the plane across two possible corridors - in the north to the border of Kazakhstan and Turkmenistan, and a southern corridor from Indonesia to the southern Indian Ocean.

Officials involved in the multi-national investigation said the probe would also focus on regions with disused airports equipped with long runways.

“There are two likely possibilities - either the plane landed somewhere and the engine was shut down or it crashed.”

“As soon as the first country comes up with evidence of the flight’s position after its last confirmed position (320km northwest of Penang), we will be able to refine the search and better determine its possible location,” the officials said.

The mystery of the missing plane from Kuala Lumpur to Beijing since March 8 continued to baffle aviation and security authorities who have not succeeded in tracking the aircraft despite deploying hi-tech radar and other gadgets.

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